<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    开学季马上到了，笔记本电脑不要<del>9998</del>元，只要<strong>998</strong> <br>

    <!-- 下标 -->
    H<sub>2</sub>O 

    <!-- 上标 -->
     3<sup>2</sup>=9
    <!-- pre原样输出 -->
    <pre>
        public class Hello{
            public static void main(String args[]) {
                System.out.println("Hellooworld");
            }
        }
    </pre>

    <!-- 加粗 -->
     <strong>998</strong> -- <b>998</b>    <br>
     <em>998</ins>        -- <i>998</i>    <br>
      <ins>998</ins>      -- <u>998</u>    <br>
     <del>998</del>       -- <s>998</s>    <br>
</body>
</html>